1. Field of the Invention
The present invention relates to a centrifuge instrument and in particular to a centrifuge instrument having a recognition arrangement for automatically identifying a particular rotor introduced into the centrifuge instrument.
2. Description of the Prior Art
A centrifuge instrument is a device adapted to expose a liquid sample carried in a rotating member called a rotor to a centrifugal force field. The centrifuge instrument includes a drive shaft or spindle adapted to receive any one of a predetermined plurality of individual rotors. It is important to correctly ascertain the identity of a particular rotor being used in the centrifuge instrument at any given time. Such information regarding rotor identity is important, among other things, for automatically controlling acceleration and deceleration times and for controlling the temperature of the rotor or other parameters of centrifuge operation related to the particular separation being effected in the rotor. Perhaps more importantly, however, rotor identification is vital to insure that the particular rotor being used is not rotated to a speed that presents the danger of rotor disintegration at a sufficiently high level as to breach the containment system of the centrifuge.
Presently, rotor identification may be performed manually by requiring the operator of the centrifuge to introduce information via the centrifuge instrument control panel regarding the identity of the particular rotor being utilized. This system is open to inadvertent error or deliberate misrepresentation by the operator and, thus, cannot be relied upon for providing rotor identification for any safety-related consideration.
Automatic systems for rotor identification are available. Exemplary of such systems are those shown in U.S Pat. No. 4,551,715 (Durbin) and U.S. Pat. No. 4,601,696 (Kamm). These systems utilize some form of coding elements usually disposed on the undersurface of the rotor. The coding elements are read by an appropriate optical or magnetic detector mounted in an operative location in the instrument. These systems share the disadvantage that the detector element, due to its location within the instrument, may be subject to corrosion which would vitiate its ability to accurately detect the coding elements provided on the rotor. Moreover, such a system would be inapplicable in ascertaining the identity of rotors not equipped with the appropriate coding elements. Thus, these identification systems would be unable to identify a significant population of rotors unless those rotors were retrofitted with the appropriate coding elements. Moreover, retro-fitting carries with it the risk of accidental or deliberate mismarking of the rotor and for this reason shares the same disadvantages as discussed above.
A rotor identification system, relying on the interruption of a beam of light from a source to a detector is disclosed in U.S. Pat. No. 4,450,391 (Hara).
In view of the foregoing it is believed advantageous to provide a rotor recognition system for automatically ascertaining the identity of each of a predetermined number of individual rotor elements introducible into the centrifuge instrument. Moreover, it is believed advantageous to provide such a recognition capability that is independent of the presence of coding elements on the rotors so that the entire established population of rotor elements may be identified.